New Early Eocene mammalian fauna from western Patagonia, Argentina

Two new fossil mammal localities from the Paleogene of central-western Patagonia are preliminarily described as the basis for a new possible biochronological unit for the early Eocene of Patagonia, correlated as being between two conventional SALMAs, the Riochican (older) and the Vacan subage of the Casamayoran SALMA. The mammal-bearing strata belong to the Middle Chubut River Volcanic-Pyroclastic Complex (northwestern Chubut Province, Argentina), of Paleocene-Eocene age. This complex includes a variety of volcaniclastic, intrusive, pyroclastic, and extrusive rocks deposited after the K-T boundary. Geochronological data taken from nearby volcanic deposits that underlie and overlie the mammal-bearing levels indicate that both faunas are of late early Eocene age (Ypresian-Lutetian boundary). In addition to more than 50 species of mammals, including marsupials, ungulates, and xenarthrans, two lower molars are the oldest evidence of bats in South America. Paleobotanical and palynological evidence from inferred contemporary localities nearby indicate subtropical environments characterized by warm and probably moderately humid climate. Remarkably, this new fauna is tentatively correlated with Eocene mammals from the La Meseta Formation in the Antarctic Peninsula. We conclude that the two localities mentioned above are part of a possible new biochronological unit, but the formal proposal of a new SALMA awaits completion of taxonomic analysis of the materials reported upon here. If the La Meseta fauna is correlated biochronologically to western Patagonia, this also suggests a continental extension of the biogeographic Weddelian Province as far north as central-western Patagonia

Short-Term Enrichment Makes Male Rats More Attractive, More Defensive and Alters Hypothalamic Neurons

Innate behaviors are shaped by contingencies built during evolutionary history. On the other hand, environmental stimuli play a significant role in shaping behavior. In particular, a short period of environmental enrichment can enhance cognitive behavior, modify effects of stress on learned behaviors and induce brain plasticity. It is unclear if modulation by environment can extend to innate behaviors which are preserved by intense selection pressure. In the present report we investigate this issue by studying effects of relatively short (14-days) environmental enrichment on two prominent innate behaviors in rats, avoidance of predator odors and ability of males to attract mates. We show that enrichment has strong effects on both the innate behaviors: a) enriched males were more avoidant of a predator odor than non-enriched controls, and had a greater rise in corticosterone levels in response to the odor; and b) had higher testosterone levels and were more attractive to females. Additionally, we demonstrate decrease in dendritic length of neurons of ventrolateral nucleus of hypothalamus, important for reproductive mate-choice and increase in the same in dorsomedial nucleus, important for defensive behavior. Thus, behavioral and hormonal observations provide evidence that a short period of environmental manipulation can alter innate behaviors, providing a good example of gene-environment interaction

Suppression of interferon gene expression overcomes resistance to MEK inhibition in KRAS-mutant colorectal cancer.

Despite showing clinical activity in BRAF-mutant melanoma, the MEK inhibitor (MEKi) trametinib has failed to show clinical benefit in KRAS-mutant colorectal cancer. To identify mechanisms of resistance to MEKi, we employed a pharmacogenomic analysis of MEKi-sensitive versus MEKi-resistant colorectal cancer cell lines. Strikingly, interferon- and inflammatory-related gene sets were enriched in cell lines exhibiting intrinsic and acquired resistance to MEK inhibition. The bromodomain inhibitor JQ1 suppressed interferon-stimulated gene (ISG) expression and in combination with MEK inhibitors displayed synergistic effects and induced apoptosis in MEKi-resistant colorectal cancer cell lines. ISG expression was confirmed in patient-derived organoid models, which displayed resistance to trametinib and were resensitized by JQ1 co-treatment. In in vivo models of colorectal cancer, combination treatment significantly suppressed tumor growth. Our findings provide a novel explanation for the limited response to MEK inhibitors in KRAS-mutant colorectal cancer, known for its inflammatory nature. Moreover, the high expression of ISGs was associated with significantly reduced survival of colorectal cancer patients. Excitingly, we have identified novel therapeutic opportunities to overcome intrinsic and acquired resistance to MEK inhibition in colorectal cancer

The oldest mammals from Antarctica, early Eocene of La Meseta Formation, Seymour Island

New fossil mammals found at the base of Acantilados II Allomember of the La Meseta Formation, from the early Eocene (Ypresian) of Seymour Island, represent the oldest evidence of this group in Antarctica. Two specimens are here described; the first belongs to a talonid portion of a lower right molar assigned to the sparnotheriodontid litoptern Notiolofos sp. cf. N. arquinotiensis. Sparnotheriodontid were medium- to large-sized ungulates, with a wide distribution in the Eocene of South America and Antarctica. The second specimen is an intermediate phalanx referred to an indeterminate Eutheria, probably a South American native ungulate. These Antarctic findings in sediments of 55.3 Ma query the minimum age needed for terrestrial mammals to spread from South America to Antarctica, which should have occurred before the final break-up of Gondwana. This event involves the disappearance of the land bridge formed by the Weddellian Isthmus, which connected West Antarctica and southern South America from the Late Cretaceous until sometime in the earliest PalaeogeneFil: Gelfo, Javier Nicolás. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Departamento Científico de Paleontología de Vertebrados; ArgentinaFil: Mörse, Thomas. Swedish Museum of Natural History. Estocolmo; SueciaFil: Lorente, Malena. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Departamento Científico de Paleontología de Vertebrados; ArgentinaFil: López, Guillermo Marcos. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Departamento Científico de Paleontología de Vertebrados; ArgentinaFil: Reguero, Marcelo Alfredo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Departamento Científico de Paleontología de Vertebrados; Argentin

A new Cramaucheniinae (Litopterna, Macraucheniidae) from the early Miocene of Patagonia, Argentina

A new litoptern Cramaucheniinae species, Pternoconius bondi , sp. nov., from Colhuehuapian levels of the Sarmiento Formation in Bajada del Diablo (Chubut, Argentina) is described herein. The specimen belongs to an adult animal and preserves the anterior portion of the skull with the maxillary region, some fragments of nasal bones, a small portion of the left zygomatic process, and most of the upper dentition (i.e., left P2–M3, right C, and right P1–M3). It is compared with the Deseadan species ? Coniopternium primitivum Cifelli and Soria 1983 and Pternoconius polymorphoides Cifelli and Soria 1983, and also with the Colhuehuapian species Cramauchenia normalis Ameghino and Theosodon lydekkeri Ameghino. Although the hypocone and precingulum development, the paracone and metacone heights, and the connection between paraconule and protocone are singular features, the main characters that diagnose this new species are lack of a mesostyle pillar, soft labial bending of the ectoloph, absence of the metaconule in molars, and the smaller size with respect to other species of the genus. Comparative study leads us to recognize this specimen as a new species that increases the diversity of the Macraucheniidae in the early Miocene of Patagonia.Fil: Cheme Arriaga, Lucas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; ArgentinaFil: Dozo, Maria Teresa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; ArgentinaFil: Gelfo, Javier Nicolás. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo; Argentin

Eocene mammals from western Patagonia.

43 p. : ill., map ; 26 cm. "March 31, 2009." Includes bibliographical references (p. 38-43).Two new fossil mammal localities from the Paleogene of central-western Patagonia are preliminarily described as the basis for a new possible biochronological unit for the early Eocene of Patagonia, correlated as being between two conventional SALMAs, the Riochican (older) and the Vacan subage of the Casamayoran SALMA. The mammal-bearing strata belong to the Middle Chubut River Volcanic-Pyroclastic Complex (northwestern Chubut Province, Argentina), of Paleocene-Eocene age. This complex includes a variety of volcaniclastic, intrusive, pyroclastic, and extrusive rocks deposited after the K-T boundary. Geochronological data taken from nearby volcanic deposits that underlie and overlie the mammal-bearing levels indicate that both faunas are of late early Eocene age (Ypresian-Lutetian boundary). In addition to more than 50 species of mammals, including marsupials, ungulates, and xenarthrans, two lower molars are the oldest evidence of bats in South America. Paleobotanical and palynological evidence from inferred contemporary localities nearby indicate subtropical environments characterized by warm and probably moderately humid climate. Remarkably, this new fauna is tentatively correlated with Eocene mammals from the La Meseta Formation in the Antarctic Peninsula. We conclude that the two localities mentioned above are part of a possible new biochronological unit, but the formal proposal of a new SALMA awaits completion of taxonomic analysis of the materials reported upon here. If the La Meseta fauna is correlated biochronologically to western Patagonia, this also suggests a continental extension of the biogeographic Weddelian Province as far north as central-western Patagonia.Published by the American Museum of Natural History, New York, NY

New early Eocene mammalian fauna from western Patagonia, Argentina /

no. 363